PANGNIRTUNG, Nunavut — Hundreds of Canadian troops were all around. Helicopters swooped over the tin roofs of this isolated hamlet. A navy frigate and coast guard icebreaker were moored and readied in a nearby fjord.

Across the bay, Master Cpl. Carl Gale was doing his part, too, as he introduced himself to an Eskimo family out picking wild blueberries.

"I suppose you know we are up here for training," he told Aluki Metuq, 31, and her four children, and then asked if they had seen any of the mock satellite debris his unit was hunting for. They had not. But the troops and their Eskimo Ranger guides gathered in a field of flowering moss anyway to join them for a snack of berries and a friendly chat before the patrol resumed.

The show of force, coupled with efforts to win over local people, showed how far the Canadian military was willing to go to familiarize itself with an increasingly valued region where it seldom operated while strengthening Canada's claim to it.

The $4 million exercise is the most prominent sign to date of Canada's intensifying effort to reinforce disputed claims over tens of thousands of miles of Arctic channels and tundra. Once nearly permanently frozen, forbidding and forgotten, the region is today seen by officials from Canada and competing nations as a potential source of both wealth and trouble.

Not all of Canada's vast claims to the Arctic are recognized internationally. The United States, the European Union and Denmark either contend that the region's waterways are open to all or have placed their own claims on parts where climate change is expected to increase access to the region's bountiful resources in coming years.

Diamond finds have already inspired a new mining rush, making Canada the world's third-largest producer. Canada wants someday to tap natural gas in the Beaufort Sea in a frigid zone, bordering Alaska and Yukon Territory, which the United States tried to auction off to oil companies last year. The companies balked, preferring not to get mixed up in an international squabble.

Despite unusual challenges from Denmark, a NATO ally, Canada is also laying claim to an Arctic island with potential oil riches off its rocky shore.

Most important, climate change has begun to make more real the dream of opening a northwest passage that would shorten ship travel between Europe and Asia by thousands of miles, over the decades to come. Canadian policy-makers want to reserve the right to regulate and tax such a passage.

"We used to forget that the Arctic was our border," Foreign Minister Pierre Pettigrew said in an interview. "There has been a change of perception of our reality, of where we belong."

But while Canada claims the region, it does not regularly patrol it. That is what Operation Narwhal was intended to remedy by making the military more comfortable operating in what can be an extreme environment and by allowing a sometimes mistrustful native population to get used to seeing Canadian troops and navy ships in Arctic waters.

For now, however, if nothing else, the exercise demonstrated that the military has a long way to go to operate effectively here.

Bad weather grounded air force planes and helicopters for days at a time, slowing troop transport even while commercial airlines kept flying. A small fire on a 40-year-old Sea King helicopter aboard the frigate Montreal hampered one exercise. Two soldiers got lost one night in the barren tundra and spent a night in a cave without survival gear.

But there were small victories, too, particularly in meshing the skills of the military and their Eskimo Ranger guides and improving relations with local residents, like Metuq and her children.

While the frigate, drones, a satellite and other patrols searched for the mock satellite debris, Tim Evic, a 45-year-old Eskimo Ranger, deciphered for Gale an otherwise inscrutable terrain where his boats could land, the intricacies of the fjord's tides, the spots where hunters and fishermen might cross and the places where patrols could find food and water.

But this is just the beginning of Canada's effort to increase its presence in the far north. Military officials have begun planning for a far more ambitious exercise in 2006 in Parry Channel, 500 miles north of the Arctic Circle.

The government has approved the launching of a satellite, Radarsat II, next year that will provide high-resolution surveillance across the Arctic to monitor the movement of surface ships. Military planners hope the satellite will work in tandem with unmanned aerial vehicles being tested during this year's exercises to see if they can provide useful intelligence despite the Arctic's low cloud cover.

Defense Minister Bill Graham noted that global warming had created "new possibilities and new threats" in the Arctic that Canada must adjust to.

"We need more resources up there and we are going to look for ways to deploy them," he said in an interview. "The sense is now the time has come."

Skeptics note, however, that even the new surveillance capacity will still not be able to detect the American, Russian, British and French nuclear submarines that periodically sail under the Arctic ice in waters claimed by Canada. Even if the submarines can be detected, the Canadian Navy does not have submarines or surface warships capable of operating in the high Arctic to do anything about it.

Seventeen years ago, the government of Brian Mulroney announced that it would buy 10 nuclear-powered submarines to prowl the disputed northern passages and upgrade five Arctic airfields to step up electronic reconnaissance flights. But the expansion was shelved in 1989 because of budget constraints.

"We have a habit of beginning northern security projects and abandoning them," noted Rob Huebert, associate director of the Center for Military and Strategic Studies at the University of Calgary.

But he said climate change, rising energy prices and increased security concerns seemed to be driving Canadian policy makers to take action.

"We're starting to get serious about surveillance in our Arctic," he added. "I finally see some action."

He compared Operation Narwhal to "baby steps" or "putting training wheels on a bike."

With the Liberal government struggling to improve health care, urban transportation and housing, however, there is little appetite in the House of Commons to significantly increase the $11 billion defense budget. The military is trying to stretch improvements on a shoestring and is staging exercises for symbolic impact.

One such operation was the "sovereignty patrol" undertaken by 20 regular Canadian troops and Eskimo Rangers in April. The patrol traveled between Resolute Bay, site of a research center on Cornwallis Island, and Alert, an outpost located at the northern end of Ellesmere Island on the Lincoln Sea. It was the longest and northernmost such operation in Canada's history.

Like these exercises, it also demonstrated both Canada's determination and its inadequate defense resources. Only 5 of the 16 mostly rented snowmobiles survived the treacherous 900-mile, two-week journey through the shifting ice and howling winds in working order. The five troopers who managed to complete the patrol hammered metal plaques into the tundra declaring Canada's sovereignty over the remote Arctic archipelago off the coast of northwest Greenland.

The patrol was Canada's response to an unlikely challenge from Denmark, which in two previous summers had landed marines from ice-cutting frigates on Hans Island, a desolate piece of rock in the Kennedy Channel, between Greenland and Ellesmere Island.

The Danes believed that the island and its surrounding waters had enough fishing and gas potential to pound Danish flags and plaques into its rocky surface and stir up a diplomatic incident that is still not settled.

Senior Canadian Defense and Foreign Ministry officials said the government viewed Hans Island as an important test case that could have repercussions for sovereignty claims along the entire Northwest Passage and the Beaufort Sea.

But there, too, the challenge is to demonstrate that Canada can not only assert its claims but also enforce them.

"If you are going to exercise your sovereignty you have to be able to show you can operate and be there," said Wayne Lord, the director of Aboriginal and Circumpolar Affairs in the Foreign Ministry. "You need the equipment and people to do something."